Gone Without a Trace: Have You Seen Baby Lisa Irwin?

Parents Deborah Bradley and Jeremy Irwin have had to watch their little girl grow up through another’s eyes.

That’s because the only picture they have to show how their daughter, Lisa, might look today — five years after the 10-month-old disappeared from her family’s home in north Kansas City, Missouri — was generated by computer.

The age-progressed image of Lisa released earlier this year by the National Center for Missing & Exploited Children “looks so much like Jeremy and me at the same time, it’s amazing,” Deborah tells PEOPLE about her daughter, who would turn 6 on Nov. 11.

“Watching your child grow up through technology is never something a parent should ever have to go through,” Deborah says in this week’s issue, on newsstands Saturday. “But if that’s all we’ve got right now, we’ll take that over nothing. We want to see her in person, and we want to take pictures of her ourselves.”

That optimism assumes a best-case outcome to which the hopeful parents cling: That Lisa was abducted in October 2011 and lives now in the caring embrace of another. Eventually, perhaps, she will be found and returned to the parents and brothers who miss her.

But that remains a scenario for which there is little known evidence.

• Subscribe now to PEOPLE or pick up the latest issue, on newsstands Saturday, for updates on the Lisa Irwin investigation.

Investigators were unable to verify a break-in at the family’s modest one-story home the night Lisa vanished — when Jeremy returned from work after 3 a.m. on Oct. 4, 2011, to find his wife and sons asleep, the front door open, lights left on and a front window screen pushed in.

Missing cell phones led to the discovery that one phone was used to call someone tied to a person of interest; witnesses also reported a man carrying an infant in the neighborhood in those early morning hours. But none of those leads have yielded answers.

Lisa’s parents also know that, as the people closest to her, questions arose about their own possible involvement, which they deny. Police have never named them as suspects.

“I’m sure there are people that think that,” Deborah tells PEOPLE, “but we know the truth, and that’s what matters.”

Adds Jeremy: “I would imagine that a lot of those people will never be heard from ever again once Lisa comes home.”

• For more on this case, watch “What Happened to Baby Lisa?” on our new true crime show, People Magazine Investigates, Nov. 14 (10 p.m. ET) on Investigation Discovery.

Asked whether authorities are investigating a missing person or homicide, Kansas City police Maj. Steve Young tells PEOPLE: “We are open to wherever the evidence takes us, and right now it’s still just an open case. But we are as hopeful as anybody that one day we’ll find this little girl.”

“As people might imagine, the volume of tips has dropped off, which is normal with a span of time,” Young says. “But that being said, it’s a case we still take very seriously.”

More than 200 tips have been logged by the National Center for Missing & Exploited Children since Lisa vanished, says Maureen Heads, program manager with NCMEC’s missing children’s division.

Deborah says media coverage surrounding last month’s fifth anniversary of the disappearance generated about 10 new tips to the family’s official website, FindLisaIrwin.com.

“That gives me hope that people are still paying attention. They’re watching. They’re still trying to help,” she says. “That means a lot to us.”

Lisa’s disappearance falls into the sliver of cases — just 3 percent last year — characterized by NCMEC as a “critical missing child,” separate from cases such as endangered runaways or suspected parental abductions.

The five-year wait for answers “obviously is not helpful for the families,” Heads says. “We want children to be recovered as quickly as possible.”

But with the examples of other disappearances where abducted children were recovered, she adds, “We are very much firm believers in never giving up, and we always hold out hope and work cases until there is a resolution.”

Says Deborah: “I feel confident with the age-progressions that [Lisa] will be recognized. We want to keep everybody out there looking for her.”

But there is also the hard fact that Lisa vanished as an infant. “When we do get her back, she’s not going to know me,” Deborah tells PEOPLE. “She’s not going to know Jeremy. She’s not going to know her brothers. But as long as she’s safe, that’s okay.”

“We can’t make up for the time that was taken from us — that was taken from her,” Deborah says. “But we can spend the rest of her life getting to know her and making her life better for her in any way we can.”